Question
The equilibrium constant for the following reaction will be $${P_{4\left( s \right)}} + 5{O_{2\left( g \right)}} \rightleftharpoons {P_4}{O_{10\left( s \right)}}$$
A.
$${K_c} = \frac{{\left[ {{P_4}} \right]{{\left[ {{O_2}} \right]}^5}}}{{\left[ {{P_4}{O_{10}}} \right]}}$$
B.
$${K_c} = \frac{1}{{{{\left[ {{O_2}} \right]}^5}}}$$
C.
$${K_c} = \frac{{\left[ {{P_4}{O_{10}}} \right]}}{{\left[ {{P_4}} \right]{{\left[ {{O_2}} \right]}^5}}}$$
D.
$${K_c} = {\left[ {{O_2}} \right]^5}$$
Answer :
$${K_c} = \frac{1}{{{{\left[ {{O_2}} \right]}^5}}}$$
Solution :
$${P_{4\left( s \right)}} + 5{O_{2\left( g \right)}} \rightleftharpoons {P_4}{O_{10\left( s \right)}}$$
Since concentration of solids is taken as 1, expression for equilibrium constant involves only oxygen.
$${K_c} = \frac{1}{{{{\left[ {{O_2}} \right]}^5}}}$$